Receiver tunable over the very high and ultrahigh frequency television bands



March 12, 1957 M. SCANDURRA 2,785,297

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RECEIVER TUNABLE OVER THE VERY HIGH AND ULTRAHIGH FREQUENCY TELEVISIONBANDS Filed March 14, 1952 7 Sheets-Sheet 5 14 E H H h I N V EN TOR.4490M Scan 20px? March 12, 1957 A. M. SCANDURRA 2,785,297

RECEIVER TUNABLE OVER THE VERY HIGH AND ULTRAHIGH FREQUENCY TELEVISIONBANDS Filed March 14, 1952 7 Sheets-Sheet 5 INVENTOR. 4100 M Jan viva;

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RECEIVER TUNABLE OVER THE VERY HIGH AND ULTRAHIGH FREQUENCY TELEVISIONBANDS 7 Sheets-Sheet 6 Filed March 14, 1952 INVENTOR. 4.400 M Jcmvm/ImMarch 12, 1957 A M. SCANDURRA 2,735,297

RECEIVER TUNABLE OVER THE VERY HIGH AND ULTRAHIGH FREQUENCY TELEVISIONBANDS Filed March 14, 1952 7 Sheets-Sheet 7 ml 1 N:

ATTORNEYS United States Patent i RECEIVER TUNABLE OVER THE VERY IHGH ANDULTRAHIGH FREQUENCY TELEVESEGN BANDS Aldo M. Scandurra, New York, N. Y.,assignor to Standard Coil Products Co., Inc., Los Angeles, Calm, acorporation of Illinois Application March 14, 1952, Serial No. 276,565

2 Claims. (Cl. 250-20) My present invention relates to UHF tuningcircuits and more particularly it relates to tuning circuits for use intelevision input tuners.

It is well-known in the art that at UHF lumped constants present avariety of undesirable or stray effects. For example, a coil forming alumped inductance presents at UHF a very complex distribution ofinterturn capacitances and its connecting leads would have considerablestray inductance. And a capacitor, on the other hand, presents manyinductive effects at its plates and at the connecting leads.

It was found that when such lumped constants were used in electricalequipment for operation at UHF they performed badly and erratically sothat transmission lines had to be used.

Outstanding examples of transmission lines heretofore used to replacelumped constants are coaxial and openwire lines, short circuited or opencircuited, having a predetermined length and generally called stubs.

Because of the shortcomings shown by lumped constants at UHF,oscillators and other tunable circuits had to use the above-mentionedtransmission lines as tuning elements with considerable increase in thecost of production of the units in addition to the increase in size ofeach unit.

Such shortcomings of lumped constants may be brought out more clearly ifa UHF oscillator is considered. Heretofore if it was desired to operatean oscillator at different UHF bands, different tank inductances wereconnected across the oscillator tank capacitance causing the oscillatorto operate from its original frequency (no oscillations) to a UHFfrequency or, in other words, shifting the point of operation of theoscillator from zero C. P. S. to, for example, 700 megacycles.

It is clear that because of this very large variation in frequency ofoperation and because of the inherent shortcomings of the lumpedconstants at UHF, the above operation was never before successfullyachieved.

To look at the problem from another point of view, it is possible tothink of the above oscillator without tuning inductance as an oscillatorhaving a resonant frequency of zero C. P. S. and of the tuninginductance to be added to the oscillator as a resonant circuit having aresonant frequency of approximately 2,000 megacycles. Combining the twoelements, namely, oscillator without tuning inductance and tuninginductance causes the combination to oscillate at a frequency locatedbetween zero and 2,000 megacycles (in this example) for example 700megacycles.

It is important to underline that the above is just an example and thatthe above numerical values were chosen to bring out more clearly thereasons why lumped constants could not be used at UHF.

In fact, from the above example it is seen first of all that if such anoscillator is to be used, its tuning element (inductance) would have tobe constructed so that it could function at a frequency of 2,000megacycles which,

2,785,297 Patented Mar. 12, 1957 or" course, is much more than the 700megacycles at which it must actually operate.

This means that the lumped constant (inductance) would have to meet muchmore stringent requirements than really is necessary for its operationat 7 00 megacycles. in fact, it was found that, for example, leadinductances and interturn capacitances may become so important as toactually obscure the tuning inductance itself, and it is also known thatfor this reason lumped constants were never used at UHF.

I overcome these problems in my present invention by using what from nowon will be referred to as incremental tuning.

Essentially, if an oscillator operating between 300 and 700 megacyclesis desired, I provide the oscillator with a fixed tuning inductance sothat without any additional electrical components it will oscillate atapproximately 500 megacycles for this example.

If I wish to operate the oscillator at any other UHF frequency withinthe above-mentioned range, I need only add in parallel to theabove-mentioned fixed inductance other electrical components,inductances or capacitances.

The reason why I can use as such electrical components lumped constantswhile never prior to this invention were lumped constants used at UHF isthat now the oscillator original frequency is not any longer at zero asin the previously described example but is 500 megacycles and,therefore, the tuning electrical component to be added to the fixedinductance need only be a circuit capable of oscillating, for example,at 1,000 megacycles so that the combination of the tuning electricalcomponent to the oscillator itself may produce a new frequency ofoscillation of 700 megacycles.

It is seen from this that the lumped electrical component to be used tochange the frequency of operation of the oscillator will now have tomeet much less stringent requirements than the abovementioned one sinceit does not have to be a resonant circuit having a resontant frequencyof 2,000 megacycles, but it must now function only as a resonant circuithaving a resontant frequency of 1,000 megacycles.

This considerably decreases all the problems presented by lumpedconstants at UHF, for example, effective lead inductances, interturncapacitances, plate inductances, etc.

Another way of looking at my present invention is to consider that whilein previous oscillators as above shown the oscillator had to operatefrom zero C. P. S. to 700 megacycles, using my present invention, theoscillator would have to shift its operating point only from 500 to 700megacycles. In other words, with my present invention, the percentage offrequency change as I vary the frequency of operation in an oscillatorbetween 300 and 700 megacycles with respect to its original operatingpoint of 500 megacycles is much less than in the previously usedoscillators in which the operating point was zero cycles per second.

An important object of my present invention is, therefore, the provisionof means whereby lumped constants may be used as tuning elements at UHF.

A more specific object of my present invention is the provision of meanswhereby lumped constants may be used as tuning elements in UHFoscillators.

My present invention is particularly adapted to be used in connectionwith UHF-VHF tuners 0f the kind shown in application Serial No. 273,720,filed February 27, 1952.

The UHF-VHF tuner shown in the above-mentioned application is of theso-called turret type adapted to receive in addition to twelve VHFchannels also seventy UHF channels.

In the above-mentioned application, all the UHF channels are dividedinto a number of bands (eight in this embodiment), each band comprisinga preselected hum 7' ber of UHF channels (in this embodiment there willbe six channels in the first band, ten in the next six bands and four inthe eighth band). All the UHF frequencies in a desired band, and if theband is, for example, the third, there will be ten such frequencies, aresimultaneously converted by my novel tunerfrom their original UHF levelto a VHF level so that their new VHF carriers correspond in thisparticular embodiment to ten preset VHF circuits.

One of these converted UHF signals is now selected by means of itscorresponding VHF circuit and converted to the intermediate frequency ofthe television set. In other words, my present invention contemplates inthe operation for reception of UHF channels a first tuning operation toselect the band in which the desired UHF channel is located. 7

By this means, actually ten UHF channels are received and converted toVHF signals, the desired UHF channel being one of these ten UHFchannels. The second tuning operation now brings about the desired UHFchannel selection from the above-mentioned ten UHF channels. The latteroperation is performed by selecting among the now VHF signals the onesignal which corresponds to the desired UHF channel.

The above-mentioned application is directed to a VHF-UHF televisioninput tuner wherein, instead of merely multiplying the number of panelsto be used in the tuner and thereby multiplying the size of the unit,two separate turrets are used inter-related electrically andmechanically so that a decimal type of operation is obtained; that is,one turret havingan appropriate number of panels is utilized for the VHFchannels; another turret with, in the present instance, eight panels isutilized in combination with the first turret for the UHF channels.

Thus, the original twelve channels can be received on the first turret.The second turret is so arranged that each panel will prepare the unitto receive a set of bands or channels While the first turret Will thenbe utilized to select channels of bands in the UHF range from the setpredetermined by the second turret.

The first turret has its tuning coils and other elements so constructedthat individual sets of panels can be utilized to tune in the twelvedifferent VHF channels. But when combined with the UHF turret, the VHFturret acts as the units portion of a decade mechanism. The UHF turretmay then, for example, be operated so that one panel will set the tuningmechanism to receive, for instance, channels 50 to 59. Then when thecircuits have been switched to this decade function, ten of the panelsof the VHF turret may be utilized to enable the operator to selectindividually channels 50, 51, 52, 53, 54, 55, 56. 57, 58 and 59 from theset of channels 50 to'59.

Where eight tuning panels are used on the UHF turret and Where ten ofthe larger number of tuning panels on the VHF turret are used incombination With the various panels on the UHF turret, it will be seenthat seventy additional UHF tuning circuits are made available by thecombination of the two turrets besides the twelve existing VHF channelsor a total of eighty-two channels. It would atfirst appear that by thisdecade mechanism and the utilization of two turrets the original twelvepanels required in a VHF tuner are increased only to twenty panels inVHF and UHF. However, owing to the gap or wide space in frequencybetween VHF channels 6 and 7, it is desirable in order to make thedecade system operative that the three additional frequencies are placedjust below channel 7. It was there found that a minimum of threeadditional panels are required for these turrets, and the chosen threepositions believed to be more suited for this purpose do not, of course,preclude the use of other positions such as above channel 13; 7

Indeed, any possible combination of ten frequencies, either utilizingVHF or newly created frequencies or combinations of both may be used. Itis also possible to use instead of turrets a switching system.

These pauelswhile they are placed on the VHF turret increasing thenumber of panels on the VHF turret to" fifteen are not used for VHFchannel selector purposes but are only used in connection with the UHFin the decade system.

In addition, although this particular way of perform ing the operationmay be varied, it was there found that a simplified switch means may beutilized controlled by the UHF turret and a space was, therefore,allocated having an angular width of one panel on the UHF turret forswitching purposes, thereby efiectively increasing the number of panelspaces on the UHF turret to nine.

Instead of a total of eightytwo panels for selecting eighty-twochannels, it was found that a maximum of twenty-four panels on twoturrets may be used for 'all channel selecting purposes as well asfor'switching from one set of channels to the other. Other arrangementscoming within the decade principle of this invention requiring more thantwenty-four panels may be employed.

This arrangement which provides for two turrets which are axiallyaligned with each other makes it possible to retain substantially thewidth and height of the original twelve channel turret type input tuner.These are the significant dimensions. p

it happens that the widest portion of the television tube itself isalways at the front of the set. The chassis is, therefore, necessarilydesigned so that most of the apparatus which need not be manuallyoperated is carried on the chassis at some distance from the front ofthe set, while the manually operable apparatus, particularly the inputtuner, is carried at the front of the set.

Since the chassis is fiat, the tube face circular and the cabinetbox-like in shape, the present turret type twelve channel input tuner,owing to the dimensional arrangements above mentioned, may be located atthe front of the set at a point located to one side of a verticaldiameter of the television tube face and below a horizontal diameterthereof and fitted into the segment of the box-like cabinet at the frontthereof not occupied by the substantially circular television tube face.

Even where a rectangular television tube is used, the 7 small dimensionof the tuning device enables its location at a point which will makepossible a reduction in the size of the cabinet. This importantdimension has to do with the height and width of the cabinet.

Longitudinally, fore and aft in the cabinet, it is possible to rearrangethe elements to provide additional space for a particular unit whererequired without increasing the size of the cabinet.

By means of this decade type turner operation utilizing coaxial-1yaligned turrets, it is possible while using the same size cabinet,chassis and tube to increase the channel selecting capabilities of thetelevision set from twelve channels to eighty-two channel Heretofore,UHF tuners were provided with a UHF oscillator to produce by one mixingoperation a signal having a carrier frequency equal to the televisionset intermediate frequency (2025 megacycles). known that at those highfrequencies, mixing can be, economically performed only by means ofcrystal mixers which have a conversion gain less than one. Actually, theconversion loss due to the crystal mixer is approximately 6 db.

It will be pointed out that R. F. amplifiers can be used beforeconversion by proper redesign.

In previous television tuners, the oscillators had to be tuned at eachchannel in which the spectrum was divided if the tuner was not of thecontinuous tuning type. In the continuous tuning type tuners, on theother hand, .it is found that the television oscillators havedilficulties in tracking to the dial and to the preselector circuit.

My novel UHF incremental tuning oscillator may be used as the local UHFoscillator ina tuner of the kind 7 described in the above-mentionedapplication since it per- It is also well' greater mits the reduction ofsuch a tuner to a very small size because of its use of lumpedconstants.

As previously mentioned, my novel UHF oscillator is connected to a fixedcircuit to which other electrical components may be successivelyconnected. When the UHF oscillator is connected only to the fixedcircuit, it oscillates at a preset frequency, located approximately inthe center of its range of operation.

When the UHF oscillator is connected to the fixed circuit and additionalelectrical components are connected to it, the oscillator will oscillateat a new preselected frequency from preselected one. Therefore, byconnecting additional and diverse electrical components to this UHFoscillator, a series of frequencies of oscillations may be obtained withwhat may be called iucrementm tuning.

In order to tune my novel television UHF oscillator, it is then onlynecessary to tune it at the above-mentioned preselected frequency sincethen it will resonate at all the other desired frequencies correspondingto the additional electrical components. For example, if the preselectedfrequency is 470 megacycles and the oscillator has to oscillate at 290,350, 410, 530, 590, 650 and 710 mcgacycles in order to tune it so thatit does actually oscillate at the above frequencies, it is necessary tofirst tune the UHF oscillator so that it oscillates at 470 megacyclcs.When this is obtained, the oscillator will resonate correctly at all theother mentioned frequencies. For extreme precision independentadjustments of capacitance and inductance of the basic oscillator mustbe made although in practice one adjustment is sufiicient.

Accordingly, a further object of my present invention is an easilytunable UHF oscillator.

More specifically, another object of my present invention is a UHFoscillator that may be calibrated for operation in a range offrequencies by calibrating it at only one preselected frequency.

l have also found that incremental tuning means may be used in bandpreselectors, making possible the .tuning operation of such bandpreselectors with lumped constants instead of distributed constants.

Another object of my present invention is, therefore, a UHF bandpreselector using lumped constants as tuning elements.

Moreover, an impedance transformation may be performed by my novel bandpreselector from a low value (for example 50 ohms) to a high level (forexample 309 ohms). This causes the UHF signals reaching the mixer to beof higher voltage than when received by the antenna.

Another object of my present invention is, therefore, a televisionUHF-VHF tuner in which the I. F. input signal to the I. F. amplifier ofthe television chassis is of greater amplitude than the signal receivedby the antenna.

Another object of my present invention is a band preselector which iscapable of passing with negligible attenuation all signals withfrequencies lying in a certain preselected band and of attenuating tosubstantially reject all other UHF frequencies.

The foregoing and many other objects of my invention will becomeapparent in the following description and drawings in which:

Figure 1 is a schematic view showing the formation of my novel decadetype television input tuner.

Figure 1A is a diagram illustrating the basic switching function for mynovel television input tuner in order to prepare it to receive VHFsignals or UHF signals.

Figure 2 is a circuit diagram corresponding to Figure 1 but showingdetails of the system and showing how pairs of coils as in Figures 4 and5 are combined to produce a selection of channel 53.

Figure 3 is a block diagram showing the relationship of the majorcircuit elements of Figure l to each other.

Figure 4 is a view of a pair of channel selector coils mounted on theirassociated panels adapted to receive channel 7 in the VHF band.

FigureS is a view of a pair of coils and the panels on which they aremounted in the UHF turret and adapted to prepare the television inputtuner to receive channels 50 to 59.

Figure 6 is a tabulation showing the relationship of the frequencies ofthe two turrets.

Figure 7 is a diagram which explains further together with Figure 2 therelationship between the two tuning systems.

Figure 8 is a schematic view of the switch mechanism of Figures 1 and 2,the switch being set for VHF reception.

Figure 9 is a view corresponding to that of Figure 8 with the switch setfor UHF reception.

Figure 10 is an exploded view of the double turret arran gement inperspective.

Figure 11 is a longitudinal cross-section through the tuner of Figure10.

Figure 12 is a transverse cross-section through the tuner of Figure 10.

Figure 13 is a front elevation of the tuning knob arrangement of Figure12.

Referring first to Figure 1, I have here shown my novel decade operatingaligned double turret television VHF- UHF input tuner set for VHFoperation.

Certain other figures should, however, be referred to briefly solely forthe purpose of conveying an idea of the appearance and function of thebasic structure to aid in understanding Figure 1.

The actual conformation of the turrets 16, 11 is shown in Figure 13 anda preliminary inspection of Figure 10 will serve to show that eachturret is individually rotatable and carries a plurality of panels 12,13 for turret 1G, and 14, 15 for turret 11. Each of these panels, ashereinafter described, carries tuning elements (examples of which areshown in Figures 2, 4 and 5) which may be utilized for channelselection. Each panel 12, 13, 14, 3.5 also has a plurality of contacts21 adapted at a specific angular position of the turret 1G or 11 toengage stationary contacts 22 to establish predetermined circuits.

The switch 30 which effects the change-over from VHF to UHF and viceversa is seen in cross-section in Figure 12 and in operative schematicin Figures 8 and 9 but is shown only in diagrammatic form in Figure 1.

Also, an examination of Figure 1A will show that the basic function ofswitch 30 is: (1) in the V position to transmit a VHF signal from theantenna directly to the VHF circuit elements while cutting out the UHFelements; and (2) in the U position to transmit a UHF signal from theantenna directly to the UHF circuit elements from which after the signalhas been converted into a VHF signal which may match the frequency orfrequencies to which the VHF tuning elements may be tuned, it istransmitted directly to the VHF circuit elements. A portion of the VHFtuning elements is always used. The UHF tuning elements, on the otherhand, are connected between the antenna and the VHF tuning elements onlywhen a UHF signal is to be received.

As shown in Figure 1A, with the switch Si) in the V position, incomingtelevision signals are impressed upon the particular tuning panelillustrated. The VHF turret here shown will as is now well-known andillustrated in the above patent select one of the twelve televisionchannels depending upon the switching position to which the VHF turret16 has been moved.

If now it is desired to receive a UHF television signal, the switch 34)is operated to the U position so that a predetermined range oftelevision frequency signals may be received as will be explained in thefollowing.

The oscillator for any one panel of the UHF turret will mix with aparticular one of the incoming television signals to produce outputsignals corresponding to the frequency to which the elements on thepanel of the VHF turret now in circuit connection are tuned.

The same oscillator on the UHF turret produces with 7 nine otherincoming television signals frequencies which correspond to the tunedcircuit of each of nine other panels on the VHF turret. Thus, bymaintaining the UHF turret contacts in the position shown and switchingthe VHF turret from panel to panel, the selection of ten different UHFincoming signals can be made.

By switching the UHF turret to the next panel, a further group of tendifferent UHF frequency channels is now prepared for selection in themanner described above. That is to say, the second panel on the UHFturret causes an oscillator to produce signals which mix with tendifferent UHF incoming television signals to produce ten different VHFsignals, each of which corresponds to the frequency to which anindividual one of the panels on the VHF turret is tuned.

When, therefore, the VHF turret is turned to a particular panel, thefrequency resulting from the mixing of the oscillator on the UHF turretwith one of the incom ing television signals will correspond to thefrequency to which the particular VHF panel is tuned. This then isrepeated for each of a new group of ten incoming UHF television signals.

With this preliminary explanation, the operation may now be understoodfrom Figure 1.

In general, the turrets 10 and 11 are constructed along the lines andoperate in the manner described in Patent No. 2,406,183 and will bestructurally described later.

UHF turret 11 of Figure l carries a plurality of pairs of panels 14 and15. Panels 14 may now be referred to as T section panels; panels 15 asoscillator panels.

The construction and operation of the circuit elements on these panelswill be described later. In the embodiment shown, each panel 14 has sixcontacts 21a, 21b, 21c, 21d, 21e, 21f. Each panel 15 has four contacts21g, 211:, 21 21k. w A pair of aligned panels 14 and 15 is usedsimultaneously. That is, when turret 11 is rotated to position wherepanel line 8 is under stationary contacts 22, the contacts 21:: to 21fof panel 14 and contacts 21g to to 21k of panel 15 for panel line 8 arein registry with the stationary contacts 22a to 22 and 22g to 22k,respectively.

Likewise, VHF turret 11 carries a plurality of pairs'of panels 12 and13. Panels 13 may be referred to as oscillator converter segments andpanels 12 as antenna segments. The construction and operation of thecircuit elements on these panels will be described later. In theembodiment shown, each panel 13 has six contacts 21L, 21M, 21N, 21P,21Q, 21R. Each panel 12 has five contacts 218, 211, 21U, 21V, 21W.

A pair of aligned panels 12 and 13 is used simultaneously. When turret10 is rotated to a position where panel line 6A is under stationarycontacts 22, the contacts 21L to 21R of panel 13 on panel line 6A engagestationary contacts 22L to 22R; and contacts 218 to 21W of panel 12 onpanel line 6A engage stationary contacts 228 to 22W.

VHF turret 10 is mounted on rotatable shaft 32 which may be manuallyrotated by knob 33 secured to the shaft 32. UHF turret 11 is mounted onconcentric shaft 34 which may be rotated by knob 35 secured to shaft 34.The UHF knob bears, at one point, the legend VHF. This point coincideswith the rise 36 of cam 37- secured to shaft 34 and with the dummypanels 44 and 45 on turret 11 which carry no contacts.

When the turret 11 is set at the angular position shown in Figure 1,rise 36 of cam 37 operates the operating rod 40 of switch 39 to the upor V position where the antenna is connected directly to the VHF tuningelements and the UHF tuning elements are cut out. At any other angularposition of the UHF turret 11, cam 37 permits spring 41 to drive theoperating rod 40 of switch 30 down to the U position so that the movablecontacts on operating rod 30 now open the antenna connection directly tothe VHF tuning elements and connect the antenna so that the signalpasses through the UHF tuning elements before it enters the VHF tuningelements.

The dielectric member of the fine tuner capacitor (hereinafterdescribed) is'mounted on shaft 51 which may be rotated by knob 52secured thereto.

In the setting of turret 11 shown in Figure '1, switch 30 has beenoperated to the V position for VHF rece tion.

The UHF elements have all been cut out by the removal of the contactbridge 58 from across contacts 69 and 61 and the removal of contactbridge 59 from across contacts 62 and 63. This cuts off the antennainput to the high pass filter 65 of the UHF tuning elements and therebycuts off any input signal to the UHF tuning elements including turret11. The output from the mixer of the UHF tuning elements has been cutoff by the removal of contact bridge from across contacts 71 and 72 andthe removal of contact bridge 73 from across contacts 74 and 75.

The UHF tuning elements are thus isolated on the input and output sides.The circuit connections thereof will be described in connection with theU position of switch 39.

Now, in the V position of switch 39, the signal received by antenna St?is conducted through leads 81 and 82 to contact 33 which is connected tolead 31 and to contact 84 which is connected to lead 82. Contact 83 isconnected by lead 85 to contact 86.

Actually, as seen in Figures 8, 9 and 12, contacts 83, 61, 86 and lead85 are preferably a single conductive metal strip, but they are hereshown schematically in Figure l as separate units to clarify theexplanation.

Signals from contact 86 then pass through bridging contact 87 to contact88 and then through lead 89 to contact 90 (contacts 88, 93, 90 and lead39 are also a single metal strip as seen in Figures 9, l0 and 14).

The signal energy then passes through bridging contact 70 to contact 91and through lead 92 to stationary contact 22T for turret 10. (Again,contacts 91 and 72 and lead 92 are a single metal strip.)

Signal energy from lead 82 flows to contact 84 and then through lead 109to contact 101 (contacts 84, 62, 191 and lead 1% may also be a singlemetal strip). Energy from contact 191 flows through bridging contact 102to contact 103 and then through lead MP4 to contact 105 (contacts 193,96, 105 and lead 104 may also be a single metal strip). From contact105, energy flows through bridging contact 73 to contact 112 6 andthrough lead 107 to stationary contact 22V for turret 19.

Thus, in the V position of the switch 36, antenna signal energy passesdirectly to stationary contacts 22T and 22V of turret 10 for the VHFtuning elements. The UHF tuning elements, including turret 11, are cutout at the input and output side.

When the knob 35 is rotated to any position other than the VHF position,shaft 34 and turret 11 are rotated and cam 37 carried by shaft 34 isalso rotated out of the position shown in Figure 1. Therefore, in any ofthe positions 1 to 8 of the UHF turret 11, the rise 36 of cam 37 ismoved out from under the operating rod 49 of switch 34 and spring 41then drives the operating rod 40 of switch 3t? to the U position.

This operation results in opening the direct connec-' tion from theantenna to stationary contacts 22V and 221 of the VHF turret 1d andconnecting the antenna leads 81 and. 82 directly to the high pass filter65 for the UHF circuit including the UHF turret 11. At the same time theoutput leads of the UHF circuit to contacts 71 and 75 of the switch 30are then connected to the stationary-contacts 221 and 22V of the VHFturret 10.

By this switching operation, the antenna which has, previously beenconnected in the position of Figure '1 directly to the VHF turretlt) isnow connected directly to the UHF elements and the energy from theantenna leads 81 and 82 must pass through and be operated on by the UHFelements before it reaches the VHF circuits.

In the U position of switch 39, lead 81 from antenna 83 is connectedthrough lead 85 to contact 61. Contact 61 is connected by bridgingcontact 58 to contact 60 which is then connected by lead 110 to the highpass filter 65. Similarly, lead 82 of the antenna is connected by leadIt?!) to contact 62 of the switch 39. When the switch is in the Uposition, the contact 62 is connected by bridging contact 59 to lead 111of the high pass filter 65. Leads 110 and 111 and their associatedcontacts 613 and 63, therefore, constitute the input leads for theentire UHF system including turret 11.

The output leads 112 and 113 of the UHF system are connected to contacts71 and 75 of the switch. In the V position of the switch, contact 71 iconnected by the bridging contact 70 to contact 72 which is thenconnected by lead 92 to stationary contact 22T for turret 19. Similarly,in the same position of the switch, contact 75 is connected by bridgingcontact 73 to contact 74 which is connected by lead 107 to stationarycontact 22V of the turret 11 The essential function of the UHF elementsincluding turret 11 is to convert the UHF signal received by the antenna80 into a signal which may be usable by the VHF elements. The functionof the UHF elements, therefore, is essentially to convert the UHF signalinto a VHF signal so that at stationary contacts 22T and 22V the samesignal frequency will be present as would have been present had a VHFsignal from the antenna St) been transmitted to these contacts directlyin the V shaped position of the switch 30.

The specific electrical circuits for the UHF system a well as for theVHF system are described in connection with Figure 2. Figure 3 alsoshows in simplified block diagram form the electrical operationsindicated in Figure 1 and shown specifically in Figure 2.

The specific operation of each of the major elements such as the highpass filter shown in Figure 1 will, therefore, be described in detailwith respect to Figure 2.

However, continuing with Figure l, the basic operation may be understoodby temporarily treating each complex of circuit elements in both the UHFand VHF sections as a single unit.

Therefore, output energy from the high pass filter 65 is transmitted byleads 115, 116 to the band selector 120. The band selector 120dependsfor its operation on the turret 11 or rather on panels 14 of theturret 11. That is, for each group of UHF frequencies (in the particularembodiment shown each group of UHF frequencies will constitute tenseparate channels) the tuning coils in the band selector must bechanged.

The panels 14 constitute a plurality of separate impedance networks,eight in the present instance, which may be switched into and out ofcircuit with other band selector elements as different groups of UHFfrequencies are to be selected. This operation, as above pointed out, isperformed by rotation of knob 35 which rotates shaft 34 and turret 11.The particular coils of turret 11 selected for the particular group offrequencies are determined by the particular panel 14 which underliesthe stationary contacts 22a to 22f so that the contacts of thatparticular panel may engage the stationary contacts.

Therefore, when panels along line 8 are turned by operation of knob 35,shaft 34 and turret 11 so that they underlie stationary contacts 22, 22,the coil on panel 14 for the particular line 8" is connected by thecontacts 21a to 21 for that panel, making an appropriate currentcarrying engagement with the stationary contacts 22a to 22f. Theparticular arrangement of the coils will be better seen in Figures 2, 4and 5.

Stationary contacts 22a and 2212 are bridged to the "10 single lead 122which is connected to the band selector. Contact 220 is connected bylead 123 to ground. Contact 22d is connected by lead 12:; to the bandselector. Contacts 22e and 22 are bridged to lead which is connected tothe band selector.

The three leads 122, 124 and 125 of the band selector thereby make itpossible, owing to the operation of turret 11, to switch different coilson panel 14 into circuit with the band preselector. Consequently, thecoils on panels 14 of turret 11 may simply be regarded as part of theband preselector 120 with the turret providing for a simplified meansfor switching diiferet coils into the band preselector circuit whendifferent groups of frequencies are to be received.

An independent UHF oscillator is provided in the UHF system, the purposeof which will be more fully understood from an examination of Figure 2but which may be regarded generally for the present as generating alocal frequency which may be mixed with the UHF received frequency tohavev the ultimate result of reducing the UHF frequency to a VHFfrequency which may thereafter be properly handled by the VHF tuningelements.

For this purpose, however, it is essential that for each frequency bandselected by the band preselector 120, UHF oscillator 13% should becontrolled so that an appropriate mixing may be obtained with thereceived UHF signal. This is accomplished by the plurality of coils onpanels 15 of the UHF turret 11. The contacts 21;; to 21!: on the panelscarrying these coils are arranged so that for each position of turret 11a different oscillator coil is connected to the stationary contacts ZZgto 22k.

The left half of turret 11 may, therefore, be regarded as a part of theband preselector circuit, while the right half of turret 11 carryingpanels 15 may be regarded as a part of the UHF oscillator. Stationarycontacts 22g and 2212 are bridged to lead 131 which is connected to theUHF oscillator. Stationary contacts 22 and 22]; are bridged to lead 152which is also connected to the UHF oscillator 130.

By this means, therefore, rotation of turret 11 by knob 35 results inthe simultaneous connection to the band preselector circuit 129 and theUHF oscillator circuit 13% of different coils appropriate to each otherand appropriate to the particular group of UHF frequencies which are tobe received and thereafter transmitted as a VHF signal to the VHFoperating elements for further selection, detection and amplificationinto the desired audio andvideo signal for the particular UHF channeldesired.

The UHF oscillator circuit 136 is connected by leads 137 and 138 toanother input of the band preselector 121?. The band preselector 12b isconnected by leads and 136 to the input of the mixer circuit 66. Theoutput si nal which has been thereby changed from a UHF input to anoutput which may be utilized by the VHF circuits is now transmitted byleads 112 and 113 as above mentioned to contacts 71 and 75 of the switch34? from which they are transmitted as above described to the stationaryantenna input contacts 22T and 22V of the VHF circuit.

Turning now to the specific VHF circuit, it should be understood thatthe panels 13 cooperate with the VHF oscillator 149 in the same manneras the panels 15 cooperate with the UHF oscillator 136 previouslydescribed.

Likewise the panels 12 of the VHF turret 1t. cooperate with the R. F.amplifier 1d]; in the same manner as the panels 14 cooperate with theband selector 126. There is a diiference, however, in that certain ofthe leads from panels 13 of the VHF turret 1% are to be connected to theR. F. amplifier.

As the turret 10 is rotated by knob 33 to select either individual VHFfrequencies received at antenna 80 or to select specific VHF frequencieswithin the band of UHF (converted into VHF) signals received from leads112 and 113 and contacts 71 and 75 of the UHF system, the difierentcoils on the different panels 12 and 13 are panels 12 and the contacts23L to 21R of individualpanels limay be moved into engagement with thecorresponding similarly lettered stationary contacts 22.

The signal energy input as above pointed out is at stationary contacts22T and 22V which engage similar contacts 231T and 21V on the particularpanel 12 which is brought to rest in registry with the stationarycontacts. Stationary contacts 223 and 22W are connected by leads 143 andto an input of the R. F. amplifier 141. Stationary contact 22U isconnected by lead 345 to ground.

The contacts 21L and 21M on the particular panel which is in registrywith the stationary contacts 22 are connected by stationary contacts221. and 22M and their respective leads 148 and 14-9 to the VHFoscillator circuit 14%.

Similarly, the contacts 21?, 21Q and 21R and the leads 159 and areconnected to another input of the R. F. amplifier circuit 141. Theoutput of the R. F. amplifier 141 is connected by leads 152 and 153 toan input of. the converter circuit 154. The output of the VFH oscillator14% is connected by leads 156 and 157 to another input of the convertercircuit 15 The converter circuit 154, however, requires that for eachVHF frequency which is to be received by the VHF circuit a dilferentcoil be utilized in the converter circuit 154.

Consequently, the coils on panels 13 are so arranged that as turret itis rotated to successive positions, a different coil is switched intothe converter circuit at each successive position. This coil on eachpanel 13 is connected to contacts ZEN and 21? connected to thestationary contacts ZZN and 22? which are connected by leads 16d and 161to the converter circuit 154 so that the converter circuit may also beappropriately tuned to the desired VHF frequency to cooperate properlywith the VHF oscillator circuit 14-6 and the R. F. amplifier circuit141.

The output of the converter circuit is now used in the well-known Way toproduce appropriate video and audio signals. As indicated schematicallyin Figure l, the output of the converter circuit 154 is connected byleads 165 and 166 to the I. F. amplifier 167. The I. F. amplifier isconnected by leads 16S and 3.69 to the video detector circuit 17%. Thevideo detector circuit 170 is connected by leads i7 and 172 to the videoamplifier circuit 173.

Video amplifier circuit 1 3 is connected by leads 174 and 175 to thedeflecting coil assembly 176 of the cathode ray tube 177.

Any appropriate power supply 18%) may be used for all of the circuitelements thus far described; in particular the power supply 180 is shownconnected by leads 181 and 182 to the cathode ray tube 177 as the powersupply therefor.

The output of I. F. amplifier 167 is also connected; by leads 185 and186 to the audio detector circuit 190 which in turn is connected byleads 191, 192 to the audio amplifier circuit 193. The audio amplifiercircuit 1% is connected by leads 194, 1% to the speaker 196.

The system may now be understood. The specific circuit arrangements andthe specific structural arrangements are themselves novel and important;but they are all subservient to and carry out the system of Figure 1.

Referring in fact to Figure 1 and assuming first that a VHF channel isdesired, the UHF knob 35 is turned to the position shown in Figure 1 sothat switch operating cam 37 which rotates with sleeve 34 operated byknob 35 and carrying also UHF turret 11 moves rod 49 of switch 30 sothat the contacts of switch 34) are positioned as shown in Figure 1.

As previously mentioned, the function of switch 3% is twofold. In fact,switch 39 serves not only to connect the antennas into the VHF sectionor the UHF section of the tuner, depending on what band is desired, butserves also to connect the output of, the UHF section of the tuner intothe input of the VHF section of the tuner.

Antenna system 80 actually comprises two antennas, a UHF antenna and aVHF antenna. In fact, it is wellknown in the art that the physicalstructure of the antennas is a definite function of the wave length orhe quency at which the antenna is supposed to operate and since the VHFband covers approximately 150 megacycles the highest frequency being 216megacycles, while the UHF frequency band covers approximately .450.megacycles with the lowest frequency being 470 megacycles. there is agreat separation between the VHF band and the. UHF band, and thereforeconsiderable difference in the wave length of the VHF signals and theUHF signals.

7 While antenna system 3% must comprise two antennas, with my presentsystem only one set of leads-needs to be brought into the television setfrom the antenna system 8% In fact, when as previously mentioned the UHFknob is positioned as shown in Figure 1, the contacts of switch 36 aremoved to take the position shown so that the antenna system 80 isconnected through switch 30 into the VHF tuner 10.

If new the VHF knob 33 is turned to the desired VHF channel, the signalsfrom antenna system 89 will he introduced into the correct panel 12 ofVHF turret in.

In panel '12 an electrical circuit will select the signals havingfrequencies lying in the VHF band corresponding to the channel selected.For example, if channel 7 is desired, then the electrical circuit inpanel 12 of turret JG will select and pass to the radio frequencyamplifier 141 all signals having frequencies between 174 and 180megacycles and reject or discriminate against all the other frequenciesof the VHF or UHF hands. This selection is continued through the radiofrequency amplifier 141 with the result that the amplified VHF signalsintroduced into the "converter 154 lie practically all in the correctfrequency band corresponding to the desired channel, for the aboveexample 174 to megacycies.

When knob 33 of the VHF turret it is turned to the desired channel, thecorrect VHF panel 13 will be connected across the VHF oscillator 14% sothat VHF oscillator 149 may oscillate at a preselected frequency. Theoscillator signals are fed to converter 15% and there mixed with theabove-mentioned signals from the radio frequency amplifier.

As a result of the mixing occurring at converter between the VHFoscillator signals and the VHF signals from the radio frequencyamplifier 141, the modulated signals arriving at intermediate frequencyamplifier 1-5? will have a new carrier frequency which may have anydesired range such as from 20 to 25 megacycles or approximately from 40to 45 megacycles depending on the preselected values at which theintermediate frequency amplifiers 167 are tuned.

If fine tuning should be desired at this point, by rotation of knob52,.dielectric 59 of. the fine tuning capacitor hereinafter describedwill be moved to change the capacitance of this capacitor and,therefore, provide the re.- quired fine tuning.

To summarize the above, in order to receive a VHF channel with my noveltuner, it is necessary: (1) to turn for example, channel 44, the UHFknob 35 is turned so.

that turret 11 brings the correct panels 14 and 15in contact with theUHF band preselector 129 and the UHF oscillator 134 v 7 Since cam 37 ismounted on sleeve 34 carrying turret 11, on rotation of turret 11, cam37 will also rotate, permitting rod 49 of switch 39 to go to its Uposition. When switch 39 is in the U position, then antenna systern 86is connected through contacts of switch 3% to the high pass filter 65.High pass filter 65 serves to discriminate between the VHF signals andthe UHF signals, and it will be needed whenever the UHF antenna orantenna system 8% is so positioned that it picks up not only UHF signalsbut also VHF signals. High pass filter 65 will have to attenuate tosubstantially reject all the VHF signals and pass with the leastpossible attenuation all the UHF signals from approximately 470megacycles to 960 megacycles.

It is, therefore, seen that the output of high pass filter 65 willsubstantially attenuate all but the UHF signals. All the UHF signalspicked up by antenna system 86, therefore, pass through attenuation allthe UHF signals from approximately 470 megacycles to 900 megacycles.

It is, therefore, seen that the output of high pass filter 65 willcontain only UHF signals. All the UHF signals picked up by antennasystem 8-3, therefore, pass through high pass fdter 55 and go into theband preselector 123 and if, as previously mentioned, UHF knob 35 isturned to position 4, then the electrical circuit mounted on panel 14corresponding to position 4 of UHF knob 35 will be connected across bandpreselector 120 so that band preselector 12% becomes a complete bandpass filter to pass signals having frequencies lying in the UHF bandcorresponding to position 4 of UHF knob 35 which in this casecorresponds to the UHF band from 566 megacyeles to 626 megacycles.

in other words, band preselector 120 when the correct panel 14 isconnected across one set of its terminals will pass all the frequenciesbetween 566 and 626 megacycles in the present example and will rejectall the other UHF frequencies which are present in the output of thehigh pass filter 65.

At this desired position of UHF knob 35, an electrical circuit mountedon the corresponding panel 15 of turret 11 is connected across UHFoscillator 130 so that UHF oscillator 130 will oscillate at a certainpreselected desired UHF frequency, in the present example 410megacycles.

The signals from UHF oscillator 13!) and band preselector 120 are mixedin UHF mixer 66 producing now for the present example 10 VHF signals inthe frequency range 156 to 216 megacycles. All these VHF signals areintroduced again through switch 30 in its U position to the input of VHFturret 10.

As seen in the drawings, the antenna leads and leads to the VHF panelswhen disconnected act as a capacitor. However, grounding the antennaleads eliminates this capacitance which would otherwise feed signalenergy of VHF to the tuner.

In other words, it is necessary to substantially eliminate all possiblesources for picking up VHF incoming signals of the frequency to whichthe UHF is to be converted to prevent reception of the VHF on the air atthe time.

At this desired position of UHF knob 35, an electrical circuit mountedon the corresponding panel of turret 11 is connected across UHFoscillator 130 so that UHF oscillator 13% will oscillate at a certainpreselected desired UHF frequency, in the present example 410megacycles.

The signals from UHF oscillator 139 and band preselector 12B are mixedin UHFmixer 66 producing now for the present example 10 VHF signals inthe frequency range 156 to 216 megacycles. All these VHF signals areintroduced again through switch 30 in its U position to the input of VHFturret 10.

At this point it will be necessary to turn VHF knob 33 to a positionsuch that together with UHF knob 35, the preselected UHF channel isreceived and if in the present example 44 is the required channel, VHFknob 33 will have to be turned until the digit 4 is combined in its 14correct position with decade 4 of UHF knob 35 to form number 44 which isthe desired UHF channel.

When, therefore, VHF knob 33 is turned to receive channel 44, turret 10rotates until the correct set of panels 12 and 13 are connected acrossradio frequency amplifier 141, VHF oscillator 14%? and converter 154 sothat radio frequency amplifier 141 together with its corresponding panel12 passes all signals having frequencies between 180 and 186 megacyclesin the present example and attenuate to substantially reject all otherVHF signals coming from UHF mixer 66.

At the same time, VHF oscillator 140 with the corresponding panel 130connected across it will oscillate and produce signals which when mixedin converter 154 with signals coming from radio frequency amplifier 141have a carrier frequency corresponding to the intermediate frequency towhich intermediate frequency amplifiers 167 are tuned.

To summarize the UHF operation, it is thus seen that in order to receivea UHF channel it will be necessary: (1) to turn the UHF knob 35 to theband width in which the desired UHF channel is located, (2) to turn VHFknob 33 until together with UHF knob 35 the desired UHF channel numberis obtained, and (3) fine tuning knob 52 may be operated to obtain onthe screen of tube 177 the desired quality of image.

As seen from the above, when a UHF channel is desired, only rotation ofUHF knob 35 and VHF knob 33 is necessary to obtain the correct UHFchannel. This obviously is a great simplification and a great advantageover some of the existing UHF converetrs which being separate from thetelevision chassis itself and having, therefore, separate power suppliesand separate switching means require when it is desired to go from VHFto UHF reception first a considerable heating period so that such a UHFconverter may reach its operating conditions. After this firstoperation, the UHF channel will have to be obtained by rotation of knobssimilar to the operation described above.

Furthermore, while present day UHF tuners need actually two completelyseparate circuits for UHF and for VHF channels, both circuits ending inthe intermediate frequency amplifier of the television set itself, whichin Figure 1 of this description is referred to as 167, this novel tuneras above described uses the VHF circuit not only for reception of VHFsignals directly from antenna system but also for reception of VHFsignals from the UHF section 11 of this novel tuner.

In other words, when turning from VHF to UHF channels, only oneconversion is here used; a signal coming from antenna system 30 is firstconverted to a VHF signal in the .UHF section of this novel tuner andthis VHF signal is then converted for the second time into a signalhaving the carrier frequency to which the intermediate frequencyamplifiers 167 are tuned.

It is further seen that by the addition of a new turret 11 having ninepositions to the pre-existing VHF turret 10 in which though three moresets of panels 1213 have been added, it is possible to receive not onlythe original twelve VHF channels (2 to 13) but also seventy more UHFchannels.

The great versatility of this novel tuner will be further appreciated ifone considers that quite a few thousand UHF stations will be allocatedby the F. C. C. in the United States, and all these UHF stations will bein the frequency range 470 megacycles to 890 megacycles.

In other words, this novel tuner once applied to a television setpermits the use of a television set in any location in the United Statesregardless of the particular UHF or VHF channels alocated to thatparticular location since this novel tuner can receive all the VHFchannels and all the UHF channels contemplated by the F. C. C.

Referring now to Figure 3 showing a block diagram of this novel tuner,it is there seen that when a VHF channel is desired, the antenna system80 is connected through 15 switch 30 to the'cascode tuner 10, theconnection being shown by the dash line in Figure 3 and from cascodetuner. 10; the signal now'converted to the intermediate frequency of thetelevision set is sent to the television chassis itself.

When, on the other hand, a UHF channel is desired, the antenna system 80is connected to high pass filter 65 through switch 30, the connectionbeing shown schematically by the dotted line.

High pass filter 65 discriminates against any VHF signal and sends UHFsignals to the band preselector 12% which, in turn, attenuates all UHFfrequencies except those lying in a preselected band and sends theseselected frequencies into the UHF mixer 66 so that at the output ofmixer 66 there would be a VHF signal which is the result of this firstconversion which occurs in mixer 66.

This converted'VHF signal is now connected again through switch 34 intothe cascode tuner 19, the connection being shown in dashdotted line.From the cascode tuner 19, as for the reception of VHF channels, thedesired signal is introduced into the intermediate frequency amplifiersof the television set with a carrier frequency equal to the frequency towhich the intermediate frequency amplifiers are tuned.

Referring next to the detailed electrical circuit of this novel tunershown in Figure 2, it will be first assumed that switch 39 is in the Vposition so that its contacts are positioned as shown in Figure 1. Underthese conditions as can be seen from Figure 1 and as is described inconnection with Figure l, the input signals from antenna system 8 3 aretransmitted to stationary contacts 22T and 22V which are now in contactwith contacts 211" and 21V of the described panel 12 of turret 14}.

Each of the panels 12 of turretifi carry as shown in Figure 2 and morein detail in Figures 4 and two coils 20d and 291. Coils 29%) and 2&1 aremounted on panels 12 so that only contacts 21 of each panel 12 can beseen from the outside of turret 10. One coil 201 is connected tocontacts 21T and 21V. The other coil 200 is connected across contacts215 and 21W. The center point of coil 201 is connected to contact 21U.When the movable contacts 21 come into engagement with stationarycontact 22 and when the antenna switch 31 as previously mentioned is inthe V position, then antenna system 81} is connected'across coil 201through the respective engagement of contacts 221" with 221T and 22Vwith 21V.

At this position, contact 21U is connected to contact 22U which, in itsturn, is grounded to the chassis of this novel tuner. When turret is inthis position, coil 200 will beconnected across grid 2&3 of radiofrequency amplifier 2G4 and ground through variable capacitance.

205. Since coils 2 59 and 281 are wound, one around the other, they forma transformer in which coil 291 is a primary and 290 is a secondary.

When switch 33 is in the V position, primary 2431 center tapped andgrounded is connected to the antenna system 81 while coil 2% isconnected across the input of radio frequency amplifier 284. Therefore,there will appear across resistance 2%)? connected between grid 203 oftube 234 and capacitance 2135, an amplified VHF signal if thetransformer 263-2ti1 is a step up transformer.

The plate 269 of radio frequency amplifier tube 2514 is connectedthrough an inductance 210 to the cathode 211 of the second radiofrequency amplifier tube 213. Plate 209 is also connected throughcapacitance 214 and resistance 216 to the automatic gain control circuitin the drawing referred to as AGC, the connection to the AGCbeing donethrough lead 218 grounded by capacitance 219.

The VH'F amplified signal from plate 2ti9is, therefore, fed to thecathode 211 of the second radio frequency amplifier 213. The grid 220 oftube 213 is grounded through resistance 221, capacitance 222 so that theradio frequency stage consisting of the radio frequency amplifiers 204and 213 forms cascade amplifier of the type shown in application Serial-No. 211,959 filed February 20, 1951.

'Plate 224 of R. F. tube 213 is connected to stationary contact 22R andis provided with a grounding variable capacitance 225. Stationarycontact 22Q is connected to resistance 226 by-passed to ground bycapacitance 227. Resistance 226, in its turn, is connected to powersupplies ,EBBI, the connecting lead 230 having a grounding capacitor231. To the same power supply EBBi, through the same conductor 230, isconnected grid resistance 232 which is connected to grid 220 of second'R. F. tube 230.

As previously mentioned, aligned with panel 12 of turret 10 is a panel13 previously referred to also as the oscillator converter segment.

On the oscillator converter panel 13 is mounted a system of coilsconsisting of oscillator coil 235, converter coil 236 and radiofrequency amplifier coil 237. Coil 235 is connected to the outwardlyextending contacts 21L and 21M; converter coil 236 is connected tosimilar contacts 21N and ZIP and radio frequency ampli- 'fier coil 237is connected between contacts HQ and 21R.

When turret 10 is at the desired VHF channel and, of course, switch 36is in the V position, movable contacts 211, M, N, P, Q, R engage theirrespective stationary contacts 22L, M, N, P, Q, R and as it waspreviously described plate 224 of radio frequency amplifier tube 13 isconnected to stationary contact 22R while contact 22Q is connectedthrough resistance 226 to power supply Ebin. Oscillator coil 235 isconnected through contacts 21L22L to the plate 240 of oscillator tube241 while the other side of coil 235 is connected through contactsMM-22M to the grid 242 of oscillator 241 through capacitance 244. Thegrid side of capacitance 244 is in its turn connected to ground throughresistance 246 while the other side of capacitance 244 is connected toground through another capacitance 24$. Cathode 259 of tube 241 is alsoconnected to ground. Plate 240 of tube 241 is also connected throughresistance 251 to a second power supply Ebbz through conductor 252having a grounding capacitor 253. Resistor 251 is also connected to theplate 255 of converter tube 256 through resistances 258 and 259. Grid260 of tube 256 is con- 'nected to ground through three separate paths,one comprising coil 236 which is connected to grid 26% through contacts21N-22N and is connected to ground through contacts 21P22P.

The second path to ground is through the system of series resistances262 and 263, the third path being through the vertical capacitance 265.Cathode 267 of tube 256 is also connected to ground. plate 255 of tube256 through resistance 259 is the input circuit of the intermediatefrequency amplifier of the television chassis itself. This input circuitconsists of a series combination comprising a vertical inductance 270and a capacitance 271, while the second'capacitance 272 serves toby-pass to ground all the frequencies higher than the intermediatefrequency of the television set itself.

As previously shown, the local oscillator tank inductance is wound onthe same panel 13 and on the same form 275 on which the output coil 237of the radio frequency amplifier tube 213 is wound so that injectionsinto converter tube 255 through coil 236 also mounted on the sameform257 is obtained by mutual inductance coupling. V

The previously described local oscillator using tube 241 is a Colpittsoscillator having cathode 250 grounded and a vernier tuning capacitor280 from plate to ground. This vernier capacitor 280 describedhereinafter will be referred to from now on as the fine 'tuningcapacitor.

In parallel with the fine tuning capacitor 280 is a trimmingcapacitor'281 also connected between plate 240 of oscillator tube 241and ground.

As a result of the amplification and selection provided Connected to byradio frequency amplifiers 204 and 213 and of the mixing operationperformed by tube 256 on these amplified signals and signals fromoscillator tube 241, a new signal having a carrier frequencycorresponding to the intermediate frequency of the television set(between 20 and 25 megacycles for most of the presently used televisionsets) appears at the input of the intermediate frequency amplifier 167(see Figures 1 and 2).

This intermediate frequency amplifier 167 is followed by circuitsdescribed previously in connection with Figure 1.

If now a UHF channel is desired, switch 30 will be moved from theposition shown in Figure 1 to the position shown in Figure 2 so that theantenna system 80 is now connected by means of twin leads, coaxial cableor other similar cable 110-111. Lead 119 of coaxial cable 110111 isconnected to the input side of the high pass filter 65 which consists ofseries capacitances 300 and 301 and shunt inductances 302, 303, 304. Thefunction of high pass filter 65 is to attenuate all the frequenciesbelow a certain value. More particularly, it should attenuate all thefrequencies lying in the VHF spectrum. At the same time, high passfilter 65 will actually be required in a tuner only when antenna system80 is in a high VHF field strength locality.

When this occurs, then the high pass filter 65 will be necessary todiscriminate between the VHF and the UHF signals. High pass filter 65 isfollowed by a band preselector circuit 120. The band preselector 120consists of a stationary circuit 319 and a movable circuit 311 mountedon each panel 14 of UHF turret 11.

The stationary portion 310 of band preselector 1213 consists of twoinductances 313 and 314 connected in series with the center tapgrounded. The other two ends of inductances 313 and 314 are groundedthrough trimming capacitors 316 and 317, respectively. Coil 313 isconnected to stationary contacts 22a and 2217 while coil 314 isconnected to stationary contacts 22a and 22f.

Grounded center tap between coils 313 and 314 is connected to stationarycontacts 220 and 220..

When, therefore, UHF turret 11 is rotated so that the contacts 21 of thecorrect panel 14 come into engagement with the above-describedstationary contacts 22, the electrical circuit 311 mounted on panels 14will be connected to coils 313 and 314. For example, if the circuitshown in Figure 2 is mounted on panel 14, then inductance 320 will beconnected on one side to inductance 313 and on the other side to groundthrough inductance 321, while inductance 322 will be connected on oneside to inductance 314 and on the other again through inductance 321 toground.

When inductances 329, 321 and 322 are connected to the stationaryportion 310 of band preselector 120, band preselector 120 will pass allthe UHF frequencies lying within preselected limits, the limits beingdetermined by which particular panel 14 is connected to the stationaryportion 31% of band preselector 120.

In the example as previously mentioned, the band preselector should passor less UHF frequencies out of a total of 70 UHF channels.

Although I have shown the movable circuit 311 of band preselector 120 asconsisting of inductances 320, 321, 322 connected to form a T network,actually different kinds of networks can be used instead of the oneshown in Figure 2. For example, a generalized network could be usedwhere instead of coils 320, 321 and 322 impedances Z1, Z2 and Z3 areconnected to form a T section or also coil 321 may be substituted by alead to ground while coils 320 and 322 are so positioned that theybecome mutually coupled.

Any one of these three systems may be used as the movable portion 311 ofband preselector 120. High pass filter 65 is connected to bandpreselector 120 at a point 339 of coil 313, while mixer 66 comprising inthis case a crystal 332 is connected to a point 333 of coil 314. MutuofUHF oscillator 130.

ally coupled with coil 314 is the oscillator frequency injecting device335 which in this case consists of two coils, one coil 336 mutuallycoupled with coil 314. The other coil 337 is mutually coupled to thetank coil 340 UHF oscillator 139 is also a Colpitts type oscillatorwhich is provided with a stationary portion 341 and a movable portion342. Stationary portion 3 41 consists of tube 344 of which the plate 345is connected to one side of inductance 340. The cathode 346 is connectedto ground, and grid 348 is connected to ground through resistance 349and to the other side of inductance 343 through capacitances 350 and351.

To the mid point of inductance 340 is connected a resistance 353 whichin its turn is connected to power supply Ebbs. A path to ground for thehigh frequency signals is provided by capacitance 354 connected betweenresistance 353 and ground.

When no other circuit elements are connected to UHF oscillator 130, mynovel UHF oscillator will oscillate at a frequency approximatelyintermediate between the lowest frequency and the highest frequency atwhich it will have to oscillate when other circuit elements 342 areintroduced into the UHF oscillator 130.

in the present embodiment the frequency at which UHF oscillator 13% willoscillate when no other circuit elements but those connected in thestationary part 341 are used is 476 megacycles.

Incremental tuning is the technique of using the predominant frequencycontrolling element permanently mounted intothe circuit and usingcomparatively high impedance circuit elements on the turret panels tovary the operating frequency by relatively small amounts.

it will be seen that this new arrangement allows greater tolerances ofcontact resistance, inductance and capacitance variation to occur beforereaching the end of operating tolerances.

In the present state of the art, incremental tuning combined with theuse of multiple contacts allows proper operation of oscillators, bandpreselectors and other circuits to frequency higher than 1,000megacycles.

"the movable part 342 of UHF oscillator 13% may consist as shown inFigure 2 of coil 360 connected on one side to the movable contacts 21gand 21h and on the other side to movable contacts 21 and 21k. When thecontacts 21 of panel 14 are in engagement with the respective stationarycontacts 22, then the contacts 21 of panel 15 are in engagement withtheir respective stationary contacts 22 and as shown in Figure 2, itmeans that now coil 260 is connected in parallel with coil 340 throughcontacts 2lg-22g, 21h22h, 21j22j and 21k-22k.

The addition of a coil in shunt to coil 34% causes as is well-known inthe art the resonant frequency of UHF oscillator 130 to increase withrespect to the frequency of oscillation obtained when no additionalcircuit'element was added to the stationary part 341.

in my work, I have found that when using a 50 ohm source (antenna orsignal generator) I am able, by proper design of the band preselectorcircuits, to properly transform the impedance to a higher valueapproximately 300 ohms with presently available crystal mixers whichincreases the voltage available at the crystal mixer'to essentiallycompensate for the normal conversion loss at the crystal mix time.

The combination of the band preselector and the crystal mixers operatingunder these conditions operates at essentially the same output as inputvoltage.

It is, of course, understood that the capacitance needed to complete thetank circuit of oscillator of which inductance 340 is one part may beprovided by interelectrode capacitance of tube 344 plus the wiringcapacitances.

As previously mentioned, coil 337 of injecting device 335 is mutuallycoupled to inductance 340 of the tank circuit of oscillator 139, theother side 336 of the in 19 jecting device'being mutually coupled tocoil 314 of band preselector 120' so that the input signal to UHF mixer66 comprising crystal 332 will consist of the local generatedtUH'Foscillations and the UHF signals not rejected by band preselector 120.

The addition of a second coil whose resonant frequency is higher thanthe first will increase the resonant frequency of the first coil whenconnected to it. Third and fourth coils may also be added and if theresonant frequency of each new coil added is higher than the combinedresonant frequency of the other coils, the resonant frequency with theadded coil will continue to raise the resonant frequency.

Using currently available local oscillator tubes and the use of fourparallel circuits in the frequency determining elements, oscillatorfrequency above 1,300 megacycles have been obtained. a

The frequency determining elements were lumped coils and capacitancesdespite the statements in literature that lumped contacts are of littlevalue above 500 megacycles.

As a result of this mixing operation, the output signal from crystalmixer 332 will have a new carrier having a frequency in the VHF band.This signal is now fed to the input circuit of the VHF turret throughcontacts 7172 and 7 i-75 to switch 30 and through the unbalanced tobalanced transformer 370 consisting of mutually coupled coils 371 and372, coils 371 connected to crystal mixer 332 being grounded at one endand coils 372'being connected, respectively, to contacts 71 and 75 ofswitch 3% so that the signal introduced into the VHF turret 10' will bebalanced in the same way as was balanced the signal coming directly fromantenna 80.

When instead of a higher frequency of oscillation it is desired to makeUHF oscillator 130 to oscillate at a frequency 'lower than the one atwhich it oscillates when no other circuits are connected to stationarycircuit 341,

then as shown in Figure 2 on panel corresponding, for 7 example, to thethird band in which the UHF channels have been divided in thisembodiment of my present invention, a capacitance 380 is connectedacross stationary contacts 225 ,2211, 22 22k through movable contacts21g, 21h, 21j,-21k instead of inductance 360.

The introduction of a capacitance in parallel with inductance 340 causesthetotal capacitance across inductance 340- to increase, therebydecreasing the frequency of oscillation ofUHF oscillator 130 whilebefore when inductance 369 was connected in place of capacitance 380,the frequency of oscillation of oscillator 130 was increased because theparallel combination of inductances 360 and340 produces an equivalentinductance of a value less than the smaller of the two inductances 340and 360, thereby increasing the frequency of oscillation of oscillator130.

To summarize the above and referring also to Figures 6 and .7 inaddition to Figure 2, when a VHF signal is desired, switch 30 is movedto the V position so that the antenna is connected directly into thepreselected antenna segment 12 of VHF turret 10. At the same time, thecorrespondingoscillator converter segment 13 engages the stationarycontacts 22 to connect electrical cir-' cuits to the VHF oscillator 140,the radio frequency amplifier 141 and the VHF converter 154, the inputcircuit to the VHF radio frequency amplifier 141 being mutually coupledto the antenna 80 through the circuits mounted on panel 12.

As a result of the electrical operations performed by the radiofrequency amplifier at 141-, VHF oscillator 14!) and VHF converter 154,a signal having the frequency to'which the intermediate frequencyamplifier 167 is tuned will appear across the input of intermediatefrequency amplifier 167 and, therefore, produce the desired image on thecathode ray tube 177 and the corresponding sound at speaker 196.

When, on the other hand, a UHF channel is desired, switch 30 will bemoved to the position shown in Figure 2 so that the antenna System30 isconnected to the high pass filtered which as previousiy mentioned willpass only the UHF signals, attenuating to substantially'reject all othersignals. V 7

if UHF turret 11 is now positioned as shown in Figure 2, bandpreselector 129 in this particular example will pass all frequenciesbetween 686 megacycles and 746 megacycles, while oscillator 13% willoscillate at a frequency of 530 megacycles.

As a result of the mixing operation occurring at crystal mixer ten VHFsignals may appear across coil 371 connected to the output of mixer 66,the ten VHF signals of this particular example having VHF frequenciesfrom 156 to 216, each with a band width of six rnegacycles.

These VHF frequencies as can be seen in Figures 6 and 7 corresponding toten VHF channels are indicated in Figures 6 and 7 as 6A, 6B, 6C, 7, 8,9, 10, ll, 12, 13. if, therefore, now VHF turret 10 is rotated, forexample, to what in VHF reception corresponded to channel 7 (174-180megacycles) that VHF signal of the ten appearing across coil 371 oftransformer 370 which has frequencies lying between 174 and 180megacycles will appear across the input of the VHF radio frequencyamplifier 141, will mix with the VHF oscillator signal (which may have afrequency of 154 megacycles if an intermediate frequency to the'television set of 22 n egacycles is desired) and will be converted intoa signal having a frequency to which the intermediate frequencyamplifier 167 is tuned (in this example 22 megacycles) so that thedesired image will appear on cathode ray tube 177 and the desired soundwill appear at speaker 196.

As can be seen from this example, a number of VHF channels, namely 6A,6B, 6C, 7, 8, 9, l0, l1, l2, and 13 are used not only for tuning andreception of VHF signals directly from antenna 89 but also to tune VHFsignals converted from their original UHF levelby con verter 66. Whenused for UHF tuning they will be numbered as seen in Figure 6 from 0 to9, 0 corresponding to 6A and 9m channel 13.

The UHF bands, on the other hand' will be numberedfrom 1 to 8 where atband 1 the UHF oscillator 130' willoscillate at 290, megacycles while atband 8 the UHF oscillator 13% will oscillate at 710 megacycles. VHF.channels 6A, 6B and 6C do not correspond to any of the existing VHFchannels but are used and added to the original VHF channels 2, 3, 4, 5,6, 7, 8, 9, 10, 11, 12, and 13 in order to provide a tuning'range in theVHF region from 156 megacycles to 216 megacycles.

As shown in Figures 6 and 7, in order to receive a UHF signalit willonly be necessary to combine the correct UHF band; (decade numbers) withthe correct VHF channel which then corresponds to the digit of thedesired UHF channel. In other words, as previously shown, to receive UHFchannel 53,.first band 5 is selected,-

then the VHF channel is selected which corresponds to number 3 when usedtogether with UHFlturret-fi. 7

From the above, it is now evident that by the use of incremental tuning,that is, by the addition of electrical circuits to pro-existing ones, Ican obtain not only eight different preselectors 120 to pass eightdifferent bands, but I can also obtain eight frequenciesof oscillationsfor oscillator 130 and although my novel tuner will operate at UHFfrequencies between approximately 400 and megacycles by the particulararrangement of the circuit and the use of incremental tuning of theincremental networks which are for band preselector or UHF oscillator13!). l

The incremental networks may all be made of iump'ed constants, forexample, the above mentio'ned' inductances and capacitances'fo'r bandpreselector 120 and UHF oscillator 13may allbe lumped capacitancesandlumped inductances of the form well-known in the art. In other words,by the particular means used in my novel tuner, it becomes unnecessaryto use tuning elements up to the present time considered to be the onlyones operable'at UHF, namely, open-wire and stubs. It is evident, on theother hand, that if desired, open-wire transmission lines and coaxialstubs may be used in place of the lumped constants used in the presentembodiment. Furthermore, the particular type of incremental tuning isobtained in my novel tuner by controlling the coupling and the frequencyof resonance and the incremental networks which were previouslydescribed and connected to band preselector 129 and UHF oscillator 13%for each position of UHF turret 11.

More particularly, my novel incremental method for tuning the UHFoscillator 1343 to diiferent frequencies of oscillations actually may beconsidered as a displacement of resonant frequency of UHF oscillator 33%with the addition of incremental networks. This displacement of theresonant frequency is obtained by connecting to the stationary portion341 of oscillator 139 an electrical circuit having a resonant frequencydifierent from that of the fixed circuit 341. For example, it wasdescribed above that when portion 341 of oscillator 13% is not connectedto any additional network, then oscillator 130 will oscillate at 470megacycles, if now i introduced a cross portion 341 of oscillatorcircuit 130, a circuit having a frequency above 530 megacycles,.forexample, approximately 600 megacycles, will obtain a new resonantfrequency for the oscillator which is neither 470 nor 600 megacycles butwill lie between these two values, and in this particular case will havea value of 530 megacycles.

As previously mentioned, this novel incremental tuning means isapplicable also in a smaller way with more complex circuitconfigurations to the band preselector 120. It is also necessary topoint out that although in the present embodiment the oscillatorinjection device 335 was shown as two coils connected in parallel 336and 337 and the injection into coil 314 was called injection by mutualcoupling, actually this type of coupling is a very complex one; in fact,not only mutual inductive coupling but also capacitive coupling is used.

Instead of injection device 335, any other device capable of performingthe function of device 335 may be used in its place. In other words, itis not at all necessary for my novel tuner to operate successfully touse the injection device 335 shown in Figure 2 but other types ofoscillator injection may be used.

1 Referring now to Figure 4 showin a pair of VHF segments mounted ontheir respective panels adapted to receive VHF channel 7, it will beseen that radio frequency segment 12 comprises a form see on which arewound coils 2% and 231. Form 4% is cylindrical in shape and is kept inplace on the panel 12, made for example of plastic material, bysoldering the end connections of coils 2G9 and 261 to the interiorextensions dill of contacts 21. Form 4% is also secured against axialmovement by the two shoulders 453 and dil positioned at each end of form49 3 and being an integral part of panel molding 12.

Similarly, oscillator converter and radio frequency amplifier coils 235,236, 237, respectively, are mounted on a form r-I55, cylindrical inshape and of insulated substance. As in previously described panel 12,this panel 13 on which the above-mentioned coils are mounted is alsoprovided with end shoulders $527 and 4&8 which serve to secure form 4-35against axial movement. In this case too, terminals of coils 235, 236,237 are soldered to the inner extensions 41% of outwardly extendingconfact 21.

It is further seen that inside form 3-95 is positioned a lug 411externally threaded to be engaged by a wire spring 412. Lug 411 islocated internally with respect to coil 235., It is possible to producea circuit variation in the 22 frequency of oscillation of VHF oscillator140 as shown in the above-mentioned patent. I

Filaments 223 and 228 of triode combinations 24-1- 256 and 2tl4-2i3 areconnected to the filament supply (referred to in Figure 2 as 6.3v)through chokes 229 and 245, respectively. Furthermore, filament 223 isby passed to ground by capacitances 233 and 234 while the shield ofconductor 238 leading to the filament supply 6.3v is grounded at 239.

Filament 228 is also by-passed to ground by capacitance 2-5-3.

The use of only two filaments for four triodes, of course, presupposesthe use of double triodes, for example, 6BQ7 for tubes 204-213 and 616for tubes. 241 56, although any other suitable multi-electrode tube maybe successfully used. 1 a

Filament 2:47 of UHF oscillator tube 344 is grounded at one end throughchoke 24? while at the other end it is connected to the filament supplyA through choke 343.

Furthermore, filament 247 is provided with capacitance 347 bridging thetwo terminals of filament 247. To further compensate for interwireinductance, it is possible to add in parallel with choke 249 a smallinductance 352.

Referring next to Figure 5 showing the actual structure of a set ofpanels 14 and 15 of UHF turret 11 adapted to receive UHF channels 50-59and shown schematically in Figure 2, it is there seen that each panel 14and each panel 15 is provided with conductive plates 415 and 416,v

respectively.

Plate 4-15 is secured to panel 14 by soldering connections 41?; to theinternal extensions 429 of contacts 21.

Coil 321 is connected between plate 14 and coils 320 and 322. Coil 32%is connected to coil 321 at one end andto the internal extension 420 ofcontacts 21. Coil 322 is also connected at one end to coil 321 and atthe other end to the external extension 42% of contacts 21. Coil 360mounted on panel 15 is soldered to the external extensions 431 or"contacts 21 while plate 416 is secured to panel 15 through connector 423soldered to another internal extension 431 of contacts 21.

Referring now to Figures 8, 9, 11 and 12 showing the switch mechanism ofFigures 1 and 2, stationary contacts 83 and 84 are connected to theantenna system referred to in Figures 1 and 2 as 89 through leads 81 and82. tive bars as shown more clearly in Figures 11 and 12. To stationarycontacts 5t) and 63 are connected by soldering or any other suitablemeans leads 114) and 111 leading to the high pass filter 65. i As shownin Figure 10, stationary contacts 54) and 63 are also conductive bars.Another set of stationary contacts 94 and is permanently grounded bymeans of a grounding plate 430. Stationary contact 431 is schematicallyshown in Figure 8 with-the contact system referred to in Figures 1 and2' as 8339-9ll3, while stationary contact 432 represents system)6103-1ll41tl5. Actually as shown in Figure 10, contacts 431 and 432 arealso stationary conductive bars insulated in any proper way fromgrounding plate 436.

The contact system referred to in Figures 1 and 2 as 72, 91 and 92 isshown in Figures 8, 9 and 10 as stationary contact 434, while thestationary contact structure referred to in the above-mentioned figuresas 74- 161 is in Figures 9 and 10 shown as conductive bar 435. Contacts71 and 75 are also stationary in the form of a metal conductive bar. a

The movable contacts 58-59, 87-1fi2 and 70-73 as shown in Figure 10 areactually small conductive bars cmried by an insulated shaft 40, theshaft being operated as also shown in Figures 1 and 2 by cam 371 whichin its turn may be moved by rotation of knob 35.

Referring in particular to Figure 10, it is here thought necessary topoint out that movable contacts 87 and 102 while in the positioncorresponding to Figure 9 andas also shown in Figure 10 must be inperfect contact with,

tationary contacts 83 and 84 are actually conduc arenas? 23 ground plate430 if good balancing of the UHF signals is desired. It will be notedthat both contacts 87 and 102 have extensions which when switch '39 isin the position of Figure 9, position in Figures 1 and 2 referred to asposition U, make perfect contact with grounded plate 439.

The perfect grounding obtained by my novel switch 30 is necessary toeliminate the possibility that VHF signals reach the VHF turret 10during UHF operation when the contacts connecting antenna 30 to VHFturret 10 are open It is known, in fact, that because of the capacitanceexisting between switch contacts, VHF nals could be introduced to theVHF turret 163 during UHF operation through capacitance coupling betweenthe open contacts of switch 30.

' By providing the above-mentioned perfect ground, I, therefore, obtaina'grounded shield between the antenna contacts of switch 30 and the VHFcontacts of switch S-ti so that the above-mentioned capacitance couplingis completely eliminated.

The television tuner heretofore described schematically primarily inconnection with Figure 1 may more readily be seen in the exploded viewof Figure 10 and the crosssectional views of Figures 11 and 12.

It will be seen from these figures that the structure of turrets 10 and11 corresponds substantially to the structure previously described inconnection with Figure 2, and basically each of these structurescorresponds mechanically to the structure shown in the above-mentionedpatent.

' Turret 11 comprises a plurality of sets of panels 14, 15 and a centerdividing indexing disc 50%, the said disc having a plurality of notchesadapted to receive extensions of panels 14 and 15. The disc 50% issecured to shaft 34 in the UHF turret 11. Shaft 34 also carries theouter discs 501 and 520 and the spring clips 5&3, 504 which position,respectively, the outer ends of panels 14 and 15. This specific type ofmounting of the panels has been shown in the prior patent.

Shaft 34 also has secured thereto a cam 37 which as a previouslydescribed is so arranged that the rise 36 will operate the operating rod40 for switch 39 in an upward direction to disconnect the UHF panels onturretll and to connect the VHF panels on turret 10 to the antenna aspreviously described. Shaft 32 is concentric with and passes withinshaft 34, shaft 34- being a hollow shaft to permit this to occur.

The center dividing disc 510 for the panels 12 and 13 of turret 10 isfixed to the shaft 32. Panels 12 and 13 are secured in position bytheouter plates 511 and 512 and spring clips 513 and 514 in the mannerpreviously mentioned in connection with the same type of securement forthe panels of turret 11.

Shaft 32 is itself a hollow sleeve carrying rotatably within the saidshaft the shaft 51. Shaft 51 extends entirely through shaft 32 and atits outer end on the opposite side carries the dielectric member 56which is rotatable between an electrode 520 secured by rivet 521 to wall522 of chassis 525 and another electrode 526 mounted on an insulatingbutton and secured to said wali by collar 527 held in place on the wallby rivets The chassis 525 has a main top wall 530 carrying variouscircuit components including tubes for the oscillator circuits and sidewalls 531, 532. The bottom wall 535 is shaped as a hollow containeradapted when positioned over the bottom end of the side walls 531, 532as shown in Figure 12 to resiliently. engage these walls to complete astructure encasing the rotatable turrets.

Shaft 34 is received in the notch 54% of wall 543 of chassis 525 and ispositioned and retained therein by the upper edge 542 of section 543 ofbottom container 535. Shaft 32 is received in open ended slot 551 ofwall 522 of the chassis and is retained therein by the upper edge 553 ofwall 554 of the lower section535 of the chassis'enclosure. Alongitudinal spring member 552 in 24 annular recess 55%} and held byscrews 555 maintains this endof the shaft in position.

Leaf spring member 539 bears between wall 522 and dielectric member 5!}biasing dielectric member 50 against the electrode 520 of the fine tunercapacitor. The leaf spring member 560 is located at a point surroundingthe shaft 51 but below the electrode 526 so that it will not interferewith the desired variable capacitance of the fine tuner assemblycomprising electrodes 520 and 526 and dielectric member 50.

Each of the panels 12, i3, 14, and 15 is provided with a plurality ofcontact elements as indicated and numbered more specifically at Figurel, and these contact elements cooperate again as indicated and numberedat Figure l with stationary contact members 22. Stationary contactmembers 22 for the VHF turret 10 are kidney type contacts formed fromleaf spring elements supported on the insulating panel 576. Contactmembers 22 for the UHF turret 11 are similarly shaped and are supportedon the insulating panel 571.

A central divider plate 573 is carried by the chassis 525 to registerwith the divider and indexing member 510 for turret 1t and to combinewith the said divider and indexing member 510 to provide a shieldbetween the oscillator and antenna segments of the VHF turret 10.Similarly, a metallic divider 575 is provided carried by the chassis 525for the UHF turret 10 to register with the central divider and indexingplate 500 of the UHF turret 11 to comprise a complete shield between theelements on each side of the divider 560 of turret 11.

In addition, a dividing plate 539 is provided for chassis 525 having anotch 581 to pass over shaft 34. This dividing plate servessubstantially to shield the UHF turret 11 from the VHF turret ill.

The switch 3% which is operated by the operating rod 4%) and cam 37 hasbeen specifically described previously not only in connection withFigures 1 and 2 but also in connection with Figures 8 and 9and also byreference to Figures 10 and 12.

It will be seen from the cross-sectional view of Figure 12 that theentire combination turret chassis 525 may be mounted on the main chassis600 of the television set in a position where it maybe nested orinserted in part under the television tube 601. This type of mounting ofthe television tuner chassis 525 is substantially identical with themounting previously attainable with television input tuners solelyadapted to the reception of VHF signals.

Even the height of the switch 36 matches the height of the tubes andother components on the top of the chassis wall 530, which elements werepreviously present on prior input tuners adapted solely for VHF.

Consequently, the lateral and vertical'dimensions of the televisionchassis 660 and the cabinet need not be increased at all to accommodatemy novel tuner. However, as will be obvious from an examination ofFigures 7 l0 and 11, my novel tuner is longer fore and aft in thecabinet than a tuner adapted solely for VHF.

This fore and aft dimension is not critical, however, since componentsof the television receiver which need not be manually operated may bemoved to a slightly different position in order to accommodate theapproximately five inches of extra length required for my noveltelevision input tuner. Consequently, all dimensions of the televisionset may remain the same.

In Figure 12 I have also shown more specifically the operation of thespring member 41 for my novel switch 3%. While the spring 41 has beenindicated schematically merely as a compression spring in Figures 1 and2, actually as will be seen from an examination of Figure 12, spring 41is a leaf spring which engages ahook 41a on the operating rod 40 of thetelevision input tuner, biasing the operating rod 40 to the dotted lineposition shown in Figure 12 but permitting the operating rod 40 to belifted arenas? 25 tothe solid line position indicated in Figure 12 byoperationofrise36ofcam37. I

In Figures and 12 I have also shown more specifically my novel centerdivider units 510 and 5% showing how the center divider 510, forinstance, is formed by a series of arcs 610, 610 intersecting each otherat a series of apices 611. Each apex 611 corresponds to a particularpanel location and the center divider 570 is so integrated with thepanels 12 and 13 on the one turret and 14 and 15 on the other turret sothat the line of contacts of each panel will be in exact engagement withthe stationary contacts when the apex 611 associated with thatparticular panel is in registry with the detent roller 626. Detentroller 620 is mounted on a leaf spring 623 carried by the chassis 525which biases the roller 620 toward the center divider 510.

It is important that each panel location be exactly fixed. Consequently,the detent member or roller 620 must be so arranged that an exactphysical location thereof with respect to the indexing disc 510 must beobtained. Since the utilization of minute teeth on the indexing member510 and minute detents instead of roller 620 are inconsistent withrugged mechanical operation, it is necessary to devise a structure whichwill provide the same exactness while nevertheless having dependablestructural strength.

Consequenty, the inwardly directed apices 611 of the indexing disc 51%which are actually not contacted by the indexing roller 62% are utilizedto determine the exact indexing position. The roller 620 in each casewhen it comes to rest with respect to a particular inwardly directedapex 611 engages points 621 and 622 on the arc 619 on each side of theinwardly directed apex 611.

The roller is manufactured so that it is as perfectly cylindrical aspossible, and the arcuate curves 610 are cut so that they match eachother as nearly as is mechanically possible. Consequently, the roller6263 will be biased by spring 623 into a position where points 621 and622 on either side of the inwardly directed apex 611 will be equidistantfrom the inwardly directed apex 611, thereby obtaining an exact indexingof point 611 and consequently obtaining an exact positioning of theparticular set of panels associated with apex 611 so that the contactsthereof will be in exact registry with the stationary contacts.

This exact registration of the contacts is of extreme importance in theVHF and UHF frequency bands where engagement of contacts only a slightdistance from the exact predetermined point of engagement may result indetuning of the set.

All of the above structure description is primarily by way of explainingfurther the structure elements already generally described in connectionwith Figure 1, and reference to Figure 1 will serve to show once morethe relationship of the structural elements to the system thereindescribed.

As previously pointed out also in connection with Figure 1, a knob isprovided for securement to shaft 34 and operation of said shaft. A knob33 is provided for securement to shaft 32 and operation of said shaft,and a knob 52 is provided for securement to shaft 51 and operation ofsaid shaft. One form which these knobs may take is shown in Figures 11and l3.

-Essentially, it must be understood that the knobs are arranged sothat'a decade function will be indicated to the user in terms of thechannel received. In other words, the indicia visible to the user onoperation of the knobs will indicate to him whether he is, for instance,at channel 76 UHF or at channel 12 VHF. Consequently, the knobs shouldbe so arranged that they may cooperate with each other. This kind ofcooperation is, however, complicated by the fact that the positions ofturret 1t) and hence of knob 33 for turret 10 when used in VHF receptiondo not correspond numerically in a decade system to the position ofthese turrets and knobs in the UHF system.

2% This may be more fully understood from a re-examination of Figures 6and 7 wherein it will be seen that in the particular embodiment shownVHF channels 2;

3, 4, 5 and 6 are used for VHF reception only and are not combined withthe UHF channels for UHF reception. Panels 6A, 6B and 60, although theycorrespond to VHF frequencies which are adjacent VHF channels 6 and 7,are actually not used for VHF reception at all but are provided in theVHF turret in order to make possible a decade system hereinbeforementioned and described.

There would be no problem at all if there were only nine VHF channelssince then simple alternate openings.

between the alternate channel markings on the VHF knob would registerwith corresponding indicia on the UHF knob to provide an indication ofthe particular. However, since the indicia must be pre- UHF setting.sented by means of a well-known decimal numbering system while only tenparts of a quindecimal numbering system (on the VHF turret) are to beused in connection with UHF indicia to present the decimal indicia forUHF channels a more complex knob arrangement is required.

The UHF knob 35 has a large enough diameter, although masked in part bythe VHF knob 33 and by the masking member 7%, so that it may beaccessible for manual rotation. To facilitate manual rotation, the UHFknob 35 is suitably treated to permit being readily grasped bythe'fingers as, for instance, by being indented.

as at 791, 7%1 of Figure 13.

The mask is supported on the front of the cabinet by means of extensions793, 704 which space the mask away from the front of the cabinet so thatit may cover the indicia carrying sections of knobs 33 and 35. Mask 701?is provided with a window 716 through which the indicia carryingsections of knobs 33, 35 may be Visible. The mask 70% also has a centralopening 711 through which an operating knob 33a for the VHF knob 33 andintegral with the VHF knob 33 may extend.

Operating knob 33a for the VHF knob 33 is also provided with a recess33!) in which the operating knob 52 for the fine tuner shaft 51 may inpart nest, the said operating knob 52 being independently manuallyrotatable. The VHF knob 33 is provided with two rows of indicia. Theinner row of indicia 733 is for VHF channel selection. The outer row ofindicia 734 is for UHF channel selection.

A shutter 720 is provided carried by the spring member 722 which in turnis rotatably supported on pin 723 carried in opening 724 of the mask 7%.The spring member 722 is curved at 723 so that it engages the indentedsurface of knob operator 33a which is behind the mask 70%. It will beobvious that when the knob 33a is rotated in a clockwise direction withrespect to :Figure 13, the friction of the indented surface of knob 33aagainst the spring member 722 will raise the shutter 720 to the upperposition where the UHF indicia 734 are concealed by the shutter and theVHF indicia are revealed. I

Rotation in the counterclockwise direction will by the movement of thesurface of knob 33 against end 723 of; spring 722 move the shutter 72%to the down position of window 710 where the VHF indicia are concealedand the UHF antenna revealed.

In operating the set using this type of knob, it should, therefore, beunderstood that rotation in a clockwise direction will bring VHF indiciainto view. Rotation of knob 33:: in a counterclockwise direction willbring UHF indicia into view. When the device is to be turned to operatefor VHF channels only the knob 35' must first be rotated until the point725 is visible in the UHF window. Thereafter, rotation in the VHFdirection of knob 33a will provide VHF indicia.

When operating in the UHF range, the VHF knob must first be turned inthe UHF direction to reveal the

